SOIL - IT'S NOT JUST DIRT - INFORMATION

Forensic Science Project

Soil may be defined as the naturally deposited material covering the earth's surface whose chemical, physical and biological properties are capable of supporting plant growth. Soils vary widely in their composition depending on their origin and the natural forces of erosion and decomposition acting upon them over time. The factors involved in the formation of soils are:

1. living matter (plants, animals, and micro-organisms
2. climate (cold, heat, snow, rainfall, and wind)
3. parent materials (chemical and mineralogical composition)
4. relief (slope and land form)
5. time

For our purposes, soil components may be described as:

1. Sand - Sand in composed of minute rock fragments which make up the mineral portion of soil. Sand is formed through erosion of native rock materials
2. Clay - Clay is finer than sand and may feel sticky or greasy to the touch. When dried, clay becomes extremely hard.
3. Humus - Humus is composed of decomposed vegetable and animal material which is capable of holding large amounts of plant nutrients and moisture

In this activity the the relative amounts of the soil components allows for the classification of different types of soil. We will consider three types:

1. Loam - soils that contain moderate amounts of sand, clay and humus
2. Sandy Loam - soils that are predominately sand
3. Clay Loam - soils that are predominately clay
4. Humus Loam - soils that are predominately humus

In the following activity, you will perform a variety of tests that will allow you to determine the composition and type of soil you have brought from home

Return to the Student Soil - It's More Than Dirt Page